Endoscopic surgical procedures, such as arthroscopic and laparoscopic surgeries, continue to displace conventional open surgical procedures in many situations. A wide variety of surgical instruments have been developed for use in such arthroscopic and laparoscopic surgical procedures, including surgical scissors for use in cutting remotely positioned bodily tissue and other matter.
Endoscopic surgical scissors are well known in the art. In general, such scissors comprise a pair of opposing blade members adapted to open and close relative to one another, and a handle mechanism for supporting the blade members and causing them to open and close. The blade members are typically located at the distal end of the handle member, and various cutting edges, serrations or other features are provided on the blade members so as to enable them to cut the desired tissue as they open and close. The handle member typically includes an elongated midsection, whereby the cutting blades can be positioned deep within the body at a remote surgical site while the grasping portion of the handle mechanism remains outside the body for convenient engagement by the surgeon. In general, the length of the handle member's elongated midsection is determined by the depth of the surgical site, while the cross-sectional dimensions of the handle member's elongated midsection are limited by the size of the access portal leading to the interior surgical site.
Surgical scissor blades must generally be made of high strength, ductile metal materials such as stainless steels, titanium-aluminum alloys and the like so that they will retain their sharpness during use and withstand repeated high temperature sterilizations. Typically, one side of the scissor blade is provided with a sharp shearing edge which is formed by a large included angle so that the scissor blade will have the requisite structural strength and durability. The shearing edge is ground sharp so as to provide a quick, precise, and accurate cut.
Prior art surgical scissor blades have typically been manufactured by conventional stamping, forging or machining methods. More particularly, metal rod or bar stock is generally first formed into rough blanks of approximately the required size and shape. A sharp shearing edge is then carefully ground onto at least one side of the blank. This grinding step is required in order to achieve the high degree of sharpness required for surgical applications. Unfortunately, during grinding, burrs are invariably formed on the shearing edge of the scissor blade as the grinding wheel works away at the ductile metal blank. These burrs must then be carefully removed from the blade's shearing edge before the scissor blade can be used in a surgical procedure. Furthermore, after the aforementioned grinding and deburring steps, the blade must also typically be polished to the desired surface finish before use.
Burr removal is a relatively costly manufacturing step. However, it is also an absolutely necessary manufacturing step for all prior art surgical scissor blades, since any burrs left on a surgical scissor blade during manufacture could break free from the blade during surgery and thereafter become lodged in the patient's body. Thus, it is absolutely essential that all burrs, even microscopic burrs, be removed from surgical scissor blades prior to their use in surgery.
Unfortunately, the deburring process requires significant additional labor, thus slowing down the manufacturing operation and increasing cost. Furthermore, the deburring process also tends to increase scrap, since a significant amount of additional metal must generally be removed from the blade during manufacture in order to achieve a sharp shearing edge that is burr free. When the scissor blades are being formed out of relatively exotic metal alloys, this increased scrap rate can significantly increase the overall cost of producing the scissor blades.
In some surgical procedures, curved scissor blades, scissor blades with non-planar profiles, or scissor blades with customized profiles may be required. Such non-standard scissor blade configurations are generally more difficult to produce using conventional manufacturing techniques. In order to produce such non-standard scissor blade shapes using prior art manufacturing techniques, custom grinding and machining of the metal blank must frequently be performed. These additional steps tend to further increase the cost of producing the scissor blades.
In addition to the foregoing, with certain scissor designs, the surgical scissor blades must also be resilient. More particularly, in U.S. Pat. No. 5,334,198, issued Aug. 2, 1994 to Rickey D. Hart et al., surgical scissors are disclosed which comprise a pair of resilient scissor blade members. The blade members are formed so that they are in their open position when they are in their normal, relaxed state, but are capable of being elastically deformed so as to assume their closed position. It has been found that forming such resilient scissor blade members with conventional manufacturing methods can add certain complexitites and costs to the manufacturing process.
Finally, as stated above, surgical scissors are employed in many different surgical procedures currently being performed by the medical profession. The high cost of manufacturing these cutting instruments adds significantly to the overall high cost of health care in the United States, particularly in those circumstances where the surgical scissors are designed to be disposable so that they are discarded after being used in a single surgical procedure.